1) Field of the Invention.
This invention relates generally to a hitching apparatus. More particularly, the present invention relates to a post and ball type hitching apparatus.
2) Prior Art.
Post and ball type hitching apparatuses are very commonly used for the attachment of vehicles to be towed, such as a boat, trailer, etc., to the rear of a towing vehicle such as a car, truck or tractor. Common prior art post and ball type hitching apparatuses include a post which is rigidly fixed to the rear of a towing vehicle so as to extend generally vertically above a bumper or similar supporting member, and a ball fixedly attached to the post. The ball is sized to allow its insertion into a socket which is usually unitarily formed as part of a tongue or forward frame member of the vehicle to be towed. The socket is placed over the ball and secured thereto in a manner which allows rotation of the socket relative to the ball, but prevents separation thereof. This type of connection is commonly accepted as being relatively safe to use, and relatively simple to connect and disconnect.
Although post and ball type hinging apparatuses generally function well for their intended purposes, there nevertheless remains several problems which have heretofore been unaddressed, and unresolved by the prior art. For example, not all sockets which are incorporated into vehicles to be towed, are of the same size. Therefore, a single ball on a post and ball type hitching apparatus may not suffice for use with all vehicles which one may desire to tow. Because of this, it is often desirable to be able to quickly remove the ball from the post and replace it with a different size ball which will match the socket of the vehicle to be towed.
U.S. Pat. No. 4,596,406 to Van Vleet et al. discloses a quick change ball hitch apparatus which is exemplary of the prior art efforts to design a post and ball type hitching apparatus which allows for quick and simple exchange of the ball.
The ball of the Van Vleet et al. device is secured to a post by a pin, which passes through a bore centrally located through the ball and the post. The pin holds the ball in generally fixed relationship relative to the post and prevents inadvertent separation of the ball and post during use. The pin is prevented from inadvertent removal from the bore whenever a socket is placed thereover. Detachment of the ball from the post at any time during use is therefore prevented.
The disclosure of the Van Vleet et al. patent is very thorough in its description of prior art problems with regard to quick changeability of prior art hitch apparatuses, and in the advantages of a post and ball type hitch apparatus which incorporates a pin to effect connection between the post and ball thereof during use. The Van Vleet et al. patent is hereby incorporated into this disclosure by reference.
Although the Van Vleet et al. patent is somewhat successful in solving prior art problems directed to the speed and ease of exchanging balls on a post and ball type hinge apparatus, there nevertheless remain several unresolved problems with its use. One of the most important problems arises from the inability of the ball to rotate relative to the post when secured by the pin. Although in the ideal situation, it is intended that a vehicle to be towed be attached to the hitch in such a way that the socket remain rotatable relative to the ball, in actual practice, insufficient lubrication between the socket and the ball (or foreign objects trapped therebetween) can seriously inhibit or even prevent relative rotation. In such instances, the Van Vleet et al. device can easily fail due to sheer forces imparted on the pin due to a misfunctioning ball and socket connection. In other words, if in use, the socket of a towed vehicle cannot freely rotate relative to the ball of the hitch, the ball will be forced to rotate relative to the post, thus sheering the pin and allowing the ball to subsequently become disconnected from the post.
Therefore, there exists a need for a post and ball type hitch apparatus which allows for quick and easy connection and disconnection of the post and ball, yet which also allows for relative rotation of the post and ball without shearing or destruction of the connector pin.